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From Daniel Fagerstrom <>
Subject Re: [blocks] Changing component strategy
Date Tue, 24 Jan 2006 20:33:51 GMT
Carsten Ziegeler skrev:
> Daniel Fagerstrom wrote
>> WDYT?
> I'm not sure if a global registry really works. What happens if I want
> to use a block twice but with different configurations? Can this be handled?

I think this depends on your use case. A block contains components 
(services) and a servlet (which also can be thought about as a service). 
If you want your services to be collectively configured in two different 
   instances, you run into problems. But I doubt that such a case makes 
sense. Normally you want to configure a service (which in turn can 
involve lots of components in its wiring), then the service should be a 
factory rather than a singleton. And you can use the factory several 
times with different configurations.

The question is not that clear in wiring based CMs either actually. If 
you register the services with different names for the two instances you 
could as well use a global registry. If they instead have the same name, 
they must be part of disjunct dependency graphs in the blocks container. 
And then you have two completely separate applications anyway, so it 
doesn't make that much sense to deploy them together.

If the dependency graphs are not disjunct, the result of the component 
lookup must be based on some kind of search order in the graphs. Is this 
level of complication worthwhile?

I prefer the simplicity of a global registry, and the fact that OSGi use 
it is a rather good indication on that it is flexible enough.


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